Another one for the scientists.
- Thread starter yme
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what IS gravity?
can you explain it?
can you explain it?
Gravity and the strength of various degrees of gravity is one of the most difficult things to get your head around.
It is relative to the mass of an object but equally has no relevance to size only mass and density. A teaspoonful of a neutron star matter would weigh several tonnes.
ColJack said:
There is, as yet, no accepted explanation for gravity. There are theories in plenty but none that can be rigourously tested in the lab. The only thing we really think we know about gravity is that it's a property of mass - which doesn't help much because we don't know what mass is either!
One of the jobs of the large hadron collider is to find the hypothetical Higgs boson which, if it exists, will lend support to one theory of what mass is; but I'm not holding my breath.To further compound the problem, the stuff we call mass has another property, namely inertia. But here's the crunch question: are gravitational mass and inertial mass really the same thing? We only assume that they are because nobody has ever found a particle that exhibits one but not the other. Sadly, this is a poor argument because of the near impossibility of measuring the effects of gravity on individual subatomic particles.
Here's one to think about. We know from astronomical observations that gravity deflects light. We also know from lab experiments that light has momentum. Now, if the law of conservation of momentum is not to fall flat, it follows that light must also pull on the mass that deflects it. So how does it do this? Gravity without mass?
I
imamartian
is gravity a weak or a strong force? and what is fire? not a solid, liquid or a gas.... so what is it?
fire is the transitional state of one molecule into another.. namely the oxidisation of combustible material..
the atom is heated and gains energy,it separates from the other atoms that it's attached to and it then starts to attract oxygen atoms and combines with them, the excess energy being released as heat and light..
now, on to gravity...
gravity is merely electro magnetism..
everything is made of atoms, and on a smaller scale, neutrons, protons and electrons..
moving electrons produce a magnetic field..
the faster they move the more magnetism they produce..
and obviously the denser the atoms are packed together, the stronger a magnetic field it produces..
so everything on the planet is magnetised to it...
and...
and...
damnit, I had it then but I've lost my train of thought..
the atom is heated and gains energy,it separates from the other atoms that it's attached to and it then starts to attract oxygen atoms and combines with them, the excess energy being released as heat and light..
now, on to gravity...
gravity is merely electro magnetism..
everything is made of atoms, and on a smaller scale, neutrons, protons and electrons..
moving electrons produce a magnetic field..
the faster they move the more magnetism they produce..
and obviously the denser the atoms are packed together, the stronger a magnetic field it produces..
so everything on the planet is magnetised to it...
and...
and...
damnit, I had it then but I've lost my train of thought..
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imamartian said:
Interesting question that. On the subatomic scale gravity is weak; vanishingly so compared to the other known (postulated?) forces. Why this should be is one of its enigmas.
But gravity has another quirk. It's the only known force where like attracts like. On a large scale, electromagnetic and nuclear forces cancel out but gravity just keeps on adding up until it eventually overwhelms all the others, crushing atoms into neutrons and beyond. Is there a political statement in there somewhere? The insignificant masses coming together to crush their superiors? OK; forget that one.
And finally, here is yet another quirk of gravity. Consider two hollow spheres: one made of charge and the other made of mass. Outside of each there is a field while inside there is nothing. The field equations are the same in each case except for a huge difference in magnitude and, significantly, a change of sign.
If you allow the charge sphere to expand you can extract energy from it. This energy comes from that part of the external electric field which is being enveloped by the expanding sphere. Everything outside remains the same.
So far so good but now look at the mass sphere. This will not expand on its own. You have to add energy to make it grow - and yet it still swallows up external gravitational field. What do we conclude from this; that a gravitational field is full of negative energy.
The only other possibility is that the mass is going up. This is a theory crying out for experimental testing - if only we had enough mass to play with. tim west said:
That's an interesting idea. Are you thinking that maybe the mass of a light ray only intersects our 3-D space along a single line? It would then appear to have zero mass to us - but surely it would also appear to have zero gravity.
What we need here is an experiment to see whether light really does have gravity. You suspend a mass in free space and aim a laser beam to pass close by. Using a huge distance, maybe helped by multiple reflections, you confirm that the mass does indeed deflect the laser and by how much.
You also observe the mass to see whether it's accelerating towards the laser.
To give yourself any chance whatsoever, you could put the mass on a spring in a vacuum and have a laser on each side. Pulsing the lasers at the right frequency might then cause an oscillation to build up over time. How long have you got? Once again this demonstates the near impossibility of doing small scale experiments with gravity.
Maybe some day a friendly Romulan will lend us one of their engines ---There's no such thing as a friendly Romulan, there all treacherous bstrds.
Ask the Klingons.
Ask the Klingons.
